Helicopter low-g monitor, recorder and warning system

Abstract

When helicopters are accomplishing certain special maneuvers such as powered descent, or the like involving low "g" conditions, the helicopter blades may teeter excessively with respect to the mast, and under severe conditions, the mast may shear. To sense such low "g" conditions, which may be dangerous, an accelerometer is mounted on the helicopter frame close to the center of gravity of the helicopter and is coupled to data processing circuitry which classifies the low-g conditions in bands or levels of severity, recording the duration of exceedances in which the low-g conditions are below predetermined levels, and issues warning signals to the helicopter pilot through the helicopter intercom system and a suitable warning light.

What is claimed is: 
     
       1. A comprehensive digital monitoring and recording system for turbine engine powered helicopters wherein the helicopter and turbine engine have predetermined normal operating parameters, said system comprising: means for sensing the temperature of said turbine engine;   means for sensing the acceleration or "g" force acting vertically on said helicopter;   digital data processing means for determining exceedances indicating operation of said turbine engine over the normal operating temperature of said engine and when said "g" force drops below predetermined levels;   non-volatile storage means for permanently storing data giving the duration and magnitude of each said exceedance, and the total duration of the exceedances; and   means for providing a warning signal to the pilot when the "g" force reaches a predetermined low level.   
     
     
       2. A comprehensive monitoring and recording system as defined in claim 1 further including means for recording the time of occurrence of each exceedance. 
     
     
       3. A comprehensive monitoring and recording system as defined in claim 1 wherein means are provided for permanently recording the low-g exceedances in accordance with successive low-g bands below the safe acceleration level for said helicopter. 
     
     
       4. A comprehensive monitoring and recording system as defined in claim 1 further comprising means for selectively transmitting all or selected portions of the permanently stored data to a location spaced from said system, upon command. 
     
     
       5. A system as defined in claim 4 further comprising means for displaying selected data transmitted from said system. 
     
     
       6. A system as defined in claim 5 wherein said displaying means is a cockpit numerical display unit including switching means for selecting desired information to be displayed. 
     
     
       7. A helicopter low-g warning system comprising: accelerometer means for mounting in the fuselage of a helicopter for measuring vertical low-g conditions;   means for digitizing the output of said accelerometer;   memory means for storing digital information indicating predetermined dangerous helicopter low-g conditions;   digital data processing means for determining whether the digitized acceleration signals are less than the stored information indicating predetermined dangerous low-g conditions; and   means for providing a warning to the helicopter pilot when the sensed acceleration is below the predetermined dangerous low-g conditions.   
     
     
       8. A helicopter low-g warning system as defined in claim 7 including means for storing information defining a plurality of successive bands of dangerous low-g conditions; and means for providing additional warning to the helicopter pilot as the acceleration drops to lower, more dangerous bands. 
     
     
       9. A helicopter low-g warning system as defined in claim 7 further comprising non-volatile digital storage means for storing the magnitude, duration and time of each exceedance, involving low-g conditions below said predetermined low-g conditions. 
     
     
       10. A system as defined in claim 7 further including means for sensing and recording temperature exceedances involving operation of the helicopter engine above rated temperatures. 
     
     
       11. A system as defined in claim 7 further including means for sensing and recording torque exceedances involving operation of the helicopter engine above rated torque levels. 
     
     
       12. A system as defined in claim 7 further comprising non-volatile memory means for storing exceedance data relating to occasions where said low-g conditions are less than said predetermined dangerous levels. 
     
     
       13. A system as defined in claim 7 further comprising means for providing both an audio and a visual warning to the helicopter pilot. 
     
     
       14. A comprehensive digital monitoring and recording system for turbine engine powered helicopters wherein the helicopter and turbine engine have predetermined normal operating parameters, said system comprising: means for sensing the temperature of said turbine engine;   means for sensing the acceleration or "g" force acting on said helicopter;   digital data processing means for determining exceedances indicating operation of said turbine engine over the normal operating temperature of said engine and when said "g" force drops below predetermined levels;   storing data relating to each said exceedance; and   means for providing a warning to the pilot when said exceedances reach predetermined levels.   
     
     
       15. A comprehensive turbine engine monitoring and recording system as defined in claim 14 further including means for recording the time of occurrence of each exceedance. 
     
     
       16. A comprehensive turbine engine monitoring and recording system as defined in claim 14 including multiplexing means for selectively sampling a signal from said temperature sensing means and a signal from said acceleration sensing means, and means for converting the sampled signals from analog to digital form. 
     
     
       17. A helicopter low-g warning system as defined in claim 14 including means for storing information defining a plurality of successive bands of dangerous low-g conditions; and means for providing additional warning to the helicopter pilot as the acceleration drops to lower more dangerous bands. 
     
     
       18. A helicopter low-g warning system as defined in claim 14 further comprising non-volatile digital storage means for storing the magnitude, duration, and time of each exceedance, involving low-g conditions below said predetermined low-g conditions. 
     
     
       19. A system as defined in claim 14 further including means for sensing and recording torque exceedances involving operation of the helicopter engine above rated torque levels.